There has been known an automobile body comprising a floor panel which includes a front floor portion connecting a pair of laterally-spaced side-sills to one another and having a tunnel region extending longitudinally along the lateral center thereof, a rear kick-up portion extending upward from a rear end of the front floor portion, and a rear floor portion extending from an upper end of the rear kick-up portion rearward and approximately linearly. It is also generally known to provide a pair of laterally-spaced floor frames which are disposed to extend longitudinally in such a manner as to interpose the tunnel region therebetween, and joined to a bottom surface of the front floor portion, and a cross member which is disposed to extend laterally so as to connect each of the side-sills and the tunnel region, and joined to a top surface of the front floor portion.
Further, as a commonly used technique, when a pair of laterally-spaced front frames are disposed in front of the floor panel, each of the floor frames is designed to be located on a rearward extension line of a corresponding one of the front frames, in top plan view, and connect a front end of the floor frame to a rear end of the front frame, so as to allow a rearward load during a head-on collision to be effectively transmitted from the front frame to the floor frame.
Generally, each of the floor frames is disposed to extend straight or linearly and parallel to a longitudinal axis of the automobile body, and intersect orthogonally with the cross member, in top plan view. While the following Patent Publication 1 (Japanese Patent Laid-Open Publication No. 11-078959) discloses a pair of laterally-spaced floor frames each gradually inclined laterally inward toward a rear end thereof, any technical meaning of inclining the floor frames as above is not disclosed therein because a technical problem recognized therein has no direct relation with the floor frames. It would be considered that each of the front frames is designed to be simply located on a rearward extension line of a corresponding one of the front frames spaced from one another by a distance which is increased toward front ends thereof, because a technique disclosed in the Patent Publication 1 is characterized by employing a unique structure in which a subframe disposed between the pair of laterally-spaced front frames is formed in a approximately triangular shape widened toward a front end thereof in top plan view, and the frames are spaced from one another by a distance which is increased toward the front ends thereof in conformity to the shape of the subframe (gradually inclined laterally outward toward the front ends thereof).
During a head-on collision, an impact load entered rearward into each of the front frames is transmitted to the corresponding floor frame. In this process, the rearward load entered into the floor frame acts on the cross member as a bending or shear force against which the cross member has a weak resistance in terms of material dynamics. Thus, in view of effective utilization of the cross member for measures against collisions, there remains a point to be solved.